R13: 000000000000049f R14: 00000000006f8f88 R15: 0000000000000002 device bridge0 left promiscuous mode device bridge0 entered promiscuous mode IPv6: ADDRCONF(NETDEV_UP): bridge0: link is not ready device bridge0 left promiscuous mode INFO: task syz-executor0:4498 blocked for more than 120 seconds. Not tainted 4.16.0+ #10 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D20408 4498 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2862 [inline] __schedule+0x8fb/0x1ec0 kernel/sched/core.c:3440 schedule+0xf5/0x430 kernel/sched/core.c:3499 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3557 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xaad/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 lo_open+0x1b/0xa0 drivers/block/loop.c:1571 __blkdev_get+0xd51/0x13b0 fs/block_dev.c:1535 blkdev_get+0x399/0xb00 fs/block_dev.c:1609 blkdev_open+0x1c9/0x250 fs/block_dev.c:1767 do_dentry_open+0x667/0xd40 fs/open.c:752 vfs_open+0x107/0x220 fs/open.c:866 do_last fs/namei.c:3379 [inline] path_openat+0x1151/0x3530 fs/namei.c:3519 do_filp_open+0x25b/0x3b0 fs/namei.c:3554 do_sys_open+0x502/0x6d0 fs/open.c:1059 SYSC_open fs/open.c:1077 [inline] SyS_open+0x2d/0x40 fs/open.c:1072 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x40f4a0 RSP: 002b:00007fffc4f4e198 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000000000000163 RCX: 000000000040f4a0 RDX: 00007fffc4f4ef5a RSI: 0000000000000002 RDI: 00007fffc4f4ef50 RBP: 00007fffc4f4e1c0 R08: 0000000000000000 R09: 000000000000000a R10: 0000000000000075 R11: 0000000000000246 R12: 0000000000000013 R13: 0000000000000000 R14: 00000000006fd700 R15: 0000000000001380 Showing all locks held in the system: 2 locks held by khungtaskd/877: #0: (rcu_read_lock){....}, at: [<000000009b33deb7>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<000000009b33deb7>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000969f6b57>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 2 locks held by getty/4424: #0: (&tty->ldisc_sem){++++}, at: [<000000005bb057cd>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000aedce77d>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4425: #0: (&tty->ldisc_sem){++++}, at: [<000000005bb057cd>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000aedce77d>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4426: #0: (&tty->ldisc_sem){++++}, at: [<000000005bb057cd>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000aedce77d>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4427: #0: (&tty->ldisc_sem){++++}, at: [<000000005bb057cd>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000aedce77d>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4428: #0: (&tty->ldisc_sem){++++}, at: [<000000005bb057cd>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000aedce77d>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4429: #0: (&tty->ldisc_sem){++++}, at: [<000000005bb057cd>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000aedce77d>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by getty/4430: #0: (&tty->ldisc_sem){++++}, at: [<000000005bb057cd>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000aedce77d>] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2131 2 locks held by syz-executor0/4498: #0: (&bdev->bd_mutex){+.+.}, at: [<000000008ea7910d>] __blkdev_get+0x176/0x13b0 fs/block_dev.c:1458 #1: (loop_index_mutex){+.+.}, at: [<00000000fff4cd95>] lo_open+0x1b/0xa0 drivers/block/loop.c:1571 2 locks held by syz-executor7/4501: #0: (&bdev->bd_mutex){+.+.}, at: [<000000008ea7910d>] __blkdev_get+0x176/0x13b0 fs/block_dev.c:1458 #1: (loop_index_mutex){+.+.}, at: [<00000000fff4cd95>] lo_open+0x1b/0xa0 drivers/block/loop.c:1571 2 locks held by syz-executor4/4504: #0: (&bdev->bd_mutex){+.+.}, at: [<000000008ea7910d>] __blkdev_get+0x176/0x13b0 fs/block_dev.c:1458 #1: (loop_index_mutex){+.+.}, at: [<00000000fff4cd95>] lo_open+0x1b/0xa0 drivers/block/loop.c:1571 2 locks held by syz-executor5/4505: #0: (&bdev->bd_mutex){+.+.}, at: [<000000008ea7910d>] __blkdev_get+0x176/0x13b0 fs/block_dev.c:1458 #1: (loop_index_mutex){+.+.}, at: [<00000000fff4cd95>] lo_open+0x1b/0xa0 drivers/block/loop.c:1571 2 locks held by syz-executor1/19158: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000e3e4a6bd>] lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 #1: (&bdev->bd_mutex){+.+.}, at: [<00000000419c781f>] blkdev_reread_part+0x1e/0x40 block/ioctl.c:192 1 lock held by syz-executor1/19186: #0: (&bdev->bd_mutex){+.+.}, at: [<000000008ea7910d>] __blkdev_get+0x176/0x13b0 fs/block_dev.c:1458 1 lock held by syz-executor1/19188: #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000e3e4a6bd>] lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 2 locks held by syz-executor6/19165: #0: (loop_index_mutex){+.+.}, at: [<000000000f6406fd>] loop_control_ioctl+0x89/0x490 drivers/block/loop.c:1938 #1: (&lo->lo_ctl_mutex#2){+.+.}, at: [<000000006ffee79e>] loop_control_ioctl+0x1a7/0x490 drivers/block/loop.c:1952 1 lock held by syz-executor6/19189: #0: (loop_index_mutex){+.+.}, at: [<000000000f6406fd>] loop_control_ioctl+0x89/0x490 drivers/block/loop.c:1938 1 lock held by blkid/19180: #0: (&bdev->bd_mutex){+.+.}, at: [<000000008ea7910d>] __blkdev_get+0x176/0x13b0 fs/block_dev.c:1458 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 877 Comm: khungtaskd Not tainted 4.16.0+ #10 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x24d lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x123/0x180 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0x90c/0xd60 kernel/hung_task.c:249 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54